1. Field of the Invention
The present invention relates to a method, system, and program for maintaining an aggregate including active files in a storage pool.
2. Description of the Related Art
Storage management software maintains a repository for data by backing-up, archiving or migrating data from client nodes in a computer network. A storage management server stores data objects or files in one or more storage pools maintained in storage devices. The storage management server may use a database to track information about the stored files, including their location, status, policy information on the files, etc. The storage management software may also be used to restore data. The storage management software may maintain a hierarchy of storage devices, where a first level of the hierarchy includes the faster access devices, such as disk drives, storing more frequently used and accessed files. Lower levels in the hierarchy provide slower access storage devices, such as lower performance disk drives and tape drives, to store less frequently accessed or inactive data. One example of storage management software is the Tivoli® Storage Manager product marketed by International Business Machines Corporation (IBM®). (Tivoli and IBM are registered trademarks of IBM).
To improve data transfer performance, the storage management software may aggregate individual files in a storage pool, so that moving and copying operations may be performed with respect to an aggregate of files instead of single files. U.S. Pat. No. 6,098,074 describes an aggregation technique in which objects being stored are aggregated into a “managed file.” The objects may thereafter be tracked and moved as a single managed file within the storage hierarchy. When appropriate, individual objects can be processed individually such as for deletion or retrieval operations. The co-pending and commonly assigned patent application entitled “Method, System, And Program For Storing Data For Retrieval And Transfer”, having Ser. No. 10/766,576 and filed on Jan. 27, 2004, describes further techniques for managing files in aggregates.
As the amount of data users store in storage pools continues to increase, files and aggregates of files are increasingly migrated to lower levels in the storage hierarchy. Thus, data that may need to be restored may have been migrated to a slower access device, such as a tape storage media, which has a low restore performance. Further, to restore data from tape, the data may first be staged from tape to a hard disk drive pool and then restored from the hard disk drive.
Further improvements in data storage may be useful in a variety of applications.